Isomerization of hydrocarbons



United States Patent 13 tCiaims. (Cl- 260-68355) This application is adivision application of my copending application Serial No. 828,059filed July 20, 1959, now Patent No. 3,031,419, April 24, 1962.

This invention relates to a process for the isomerization ofhydrocarbons and particularly to a method for the isomerization ofstraight chain or normal paraflins.

In many instances it is preferred that saturated hydrocarbons andparticularly parafiins be in a branched chain configuration rather thana straight chain configuration. This is particularly true in the case ofparafiinic constituents of gasoline wherein paraffins contribute to ahigher octane number of the gasoline than do straight chain paraflins.Therefore it is desirable to have paraffins of the former configurationpresent and, when starting with straight chain paraflins, to have acatalyst which is capable of eifecting isomerization of said straightchain paraflins whereby a commercially attractive yield of the branchedchain paraflins will be obtained thereby.

It is therefore an object of this invention to provide a process for theisomerization of hydrocarbons in the presence of a particular catalyst.

A further object of this invention is to provide a process for theisomerization of straight chain hydrocarbons in the presence of aparticular catalytic composition of matter which is prepared in a novelmanner to provide ranched chain hydrocarbons.

One embodiment of this invention resides in a process for producingbranched chain hydrocarbons which com prises isomerizing normalhydrocarbons in the presence of a catalyst prepared by treating acomposite of a refractory inorganic oxide support containing a platinumgroup metal, the platinum group metal being characterized by being in areduced valence state, with a hydrohalide at a temperature in the rangeof from about 500 to about 650 C., thereafter vaporizing aFriedel-Crafts metal halide onto said composite, and heating the thusformed composite at a temperature above 400 C. for a time sufiicient toremove therefrom any unreacted Friedel- Crafts metal halide.

A further embodiment of this invention is found in a process forproducing branched chain hydrocarbons which comprises isomerizing normalhydrocarbons at a temperature in the range from about 0 to about 300 C.and at a pressure in the range of from about atmospheric to about 5000p.s.i. in the presence of a catalyst prepared by treating a composite ofalumina containing platinum metal, the platinum metal beingcharacterized by being in a reduced valence state, with hydrogenchloride and hydrogen at a temperature in the range of from about 500 toabout 650 C., thereafter vaporizing aluminum chloride onto saidcomposite, and heating the thus formed composite at a temperature in therange of from about 400 to about 700 C. for a time of from about 1 toabout 48 hours to remove therefrom any unreacted aluminium chloride.

A specific embodiment of this invention is found in a process forproducing isobutane which comprises isomerizing normal butane at atemperature in the range of from about 0 to about 300 C. and at apressure in the range of from about atmospheric to about 5000 psi. inthe presence of a catalyst prepared by treating a com- 7 3,112,251Patented Nov. 26, 1063 Too posite of alumina containing platinum metal,the platinum metal being characterized by being in a reduced valencestate, with hydrogen chloride and hydrogen at a temperature in the rangeof from about 500 to about 650 C., thereafter contacting said compositewith vapors of anhydrous aluminum chloride at a temperature in the rangeof from about 400 to about 700 C. for a time of from about 1 to about 48hours, whereby simultaneous reaction of the aluminum chloride with saidcomposite and heating of the resultant composite to remove unreactedaluminum chloride is accomplished as a single step.

Other objects and embodiments will be found in the following furtherdetailed description of this invention.

As hereinbefore set forth the isomerization of hydrocarbons andparticularly normal paraffins is effected in the presence of a catalystof a particular nature and which is prepared in a particular processwhich will be hereinafter set forth in greater detail. This catalyst isparticularly effective in the isomerization of paraflins andparticularly of normal parafiins such as n-butane, n-pentane, n-hexane,n-heptanc, n-octane, etc., or mixtures thereof, including isomerizationof less highly branched chain saturated hydrocarbons to more highlybranched chain saturated hydrocarbons such as the isomerization of 2- or3-methylpentane to form 2,3- and 2,2-dimethylbutane. In addition thecatalysts which are prepared in a manner according to the presentspecification may also be utilized for effecting other various reactionsof organic compounds and particularly of hydrocarbons. These reactionsinclude (A) condensation reactions in which two molecules, which may bethe same or diiferent, will condense to form larger size molecules, (3)destructive reactions in which a molecule is decomposed into a smallersize molecule or into two or more molecules, (C) rearrangement reaotionsas, for example, isomerization, (D) disproportionation reactions inwhich a radical is transferred from one molecule to another, (E)hydrogenation reactions, and (F) other reactions. Among these reactionsare (l) polymerization of olefins and particularly of ethylene,propylene, l-butene, Z-butene, isobutylene, amylene, and higher boilingolefins and mixtures thereof, (2) alkylation of isoparaffins witholefins or other alkylating agents including, for example, alkylhalides, etc., and particularly the alkylation of isobutane, isopentane,and/0r isohexane with ethylene, propylene, l-butene, 2- butene,isobutylene, amylene, etc., or mixtures thereof, (3) alkylation ofaromatics with olefins or other alkylating agents, and particularly thealkylation of benzene, toluene, etc., with propylene, butylene, amylene,and higher boiling olefins, including nonenes, decenes, undecenes,dodecenes, tridecenes, tetradecenes, pentadecenes, etc., or mixturesthereof, (4) isomerization of naphthenes, for example, the isomerizationof methylcyclopentane to cyclohexane, isomerization ofdimethylcyclopentane to methylcyclohexane, (5) alkylation of phenols orthiophenols with olefins or other alkylating agents, (6) alkylation ofthiophenes with olefins, (7) hydrogen transfer reactions, (8) alkyltransfer reactions, (9) dealkylation reactions, (10) reforming ofgasolines or naphtha to improve the antiknock characteristics thereof,(11) destructive hydrogenation reactions, (12) cracking of oil heavierthan gasoline into lower boiling products and particularly gasoline,including cracking under hydrogen pressure, (13) hydrogenation reactionsin which an unsaturated compound is hydrogenated to a more saturatedcompound, for example, the hydrogenation of diolefins to olefins,olefins to paraffins, cycloolefins to naphthenes, etc., and (14) otherreactions of hydrocarbons and organic compounds. The operatingconditions to be employed will depend upon the particular reaction andgenerally will be at relatively low temperatures although highertemperatures may be employed, particularly with atmospheric pressure.Thus, the temperature may range from 0 C. or less to 300 C. or more,preferably from 25 C. to 250 C. and the pressure may range fromatmospheric to about 5000 p.s.i. or more, preferably from 50 p.s.i. toabout 1000 p.s.i. Hydrogen may be employed when required or ofadvantage. -t is believed that hydrogen in controlled amounts may playan important role in suppressing sludge formation and in promoting manyof the reactions discussed above.

As hereinbefore set forth the isomerization of normal paraffins iscarried out in the presence of a catalyst which is prepared in a novelmanner. Heretofore Friedel-Crafts metal halide containing catalysts andvarious methods of manufacturing the same have been suggested. Thesecatalysts, while of wide commercial applicability have been ratherscarcely used inasmuch as said catalysts are possessed of relativelyshort lives and difficulty controllable activity. One such reason for arelatively short life of a catalyst of this type is that the presence ofwater in a refractory oxide-platinum group metal composite, said watertending to contaminate the catalyst by hydrolyzing the aluminum chloridewith which the composite is treated in a subsequent step.

It has now been discovered that catalysts of exceptionally high activityand long life, when utilized in the treatment of hydrocarbons, andespecially in the isomerization of normal paraiiins, may be prepared inaccordance with the method hereinafter set forth in greater detail.While the catalyst, in one stage of their preparation, are prepared fromFriedel-Crafts metal halides, they do not contain free Friedel-Craftsmetal halide as prior art catalysts of this general type have contained.In the preparation of the catalysts of the present invention, therefractory oxide containing a hydrogenation component, afterpretreatment with a hydrogen halide and, if so desired, hydrogen, andafter vaporization thereon of a Friedel-Crafts metal halide andsimultaneously or subsequently heating the composite, will be increasedin weight by from about 2 to about 10% based on the original weight ofthe refractory oxide containing a hydrogenation component. While theexact increase in weight of the refractory oxide containing ahydrogenation component does not appear to be critical within theabovementioned range, it has been found that highly active catalysts areobtained when the thus treated refractory oxide has been increased inweight from about 4 to about 8%. As stated hereinabove, the presentcatalytic composites are prepared from a Friedel-Crafts metal halide butdo not contain, after preparation, any free Friedel- Crafts metalhalide. During the preparation and simultaneous or subsequent heating,the Friedel-Crafts metal halide appears to react with the refractoryoxide containing a hydrogenation component. The simultaneous orsubsequent heating treatment is carried out at a temperature above thatrequired for vaporization of any free Friedel-Crafts metal halide fromthe surface of the catalyst at the conditions utilized.

In the first step of the process of the preparation of the catalyst ahydrogenation component, and particularly a metal of the platinum group,is incorporated into a refractory oxide. As will be shown hereinafter indetail, hydrogenation components are incorporated into refractory oxidesby various techniques including impregnation, coprecipitation,precipitation, decomposition, etc. In these various techniques for theincorporation of a hydrogenation component, particularly a platinumgroup metal, into or onto a refractory oxide such as alumina, thefinished composite of refractory oxide and hydrogenation component isusually calcined in air to fix the hydrogenation component and veryoften to dry the refractory oxide thereby simultaneously accomplishing adevelopment in the surface area thereof. Concurrently with the fixing ofthe hydrogenation component and the drying of the refractory oxide, someoxidation of the metallic hydrogenation component usually takes place.

Thus, some or all of the hydrogenation component may actually be in theform of metal oxides in which the metal occurs in various positivevalence states. These metal oxides are particularly susceptible toremoval from combinations with a refractory oxide by the passagethereover of a Friedel-Crafts metal halide such as aluminum chloride.For example, it has been found that oxides of platinum are readilystripped from combination with alumina by the passage of aluminumchloride vapors thereover. Therefore, it is necessary when utilizingsuch a composite of a refractory oxide containing a hydrogenationcomponent to insure that the hydrogenation component is in a reducedvalence state prior to vaporization of a Friedel-Crafts metal halidethereon. This can readily be carried out by the passage thereover of ahydrogen-containing gas, for example, hydrogen or hydrogen diluted withvarious inert gases, at conditions at which reduction of the metaloxides of the hydrogenation component take place. In this reducedvalence state the average valence of the metal will be in the range offrom 0 to about 0.5, more particularly the average valence of the metalbeing from about 0.1 to about 0.2. These conditions will vary over arelatively wide range depending upon the particular hydrogenationcomponent in combination with the refractory oxide and may includetemperatures of from about 250 to about 700 C. or more and pressuresranging from about atmospheric to about 100 atmospheres or more, thehigher pressures usually being associated with the lower temperaturesand vice versa. The times necessary for such treatments will depend uponwhether batch or continuous methods of operation are employed and willfurther depend upon the quantity of metal oxide and the hydrogenationcomponent present. In a continuous type operation it has been found thatthe reduction of the hydrogenation component can be satisfactorilymeasured by carrying out the hydrogenation at hydrogenation conditionsuntil no more water is removed from the hydrogenation zone. As set forthhereinabove, this necessity for the hydrogenation component being in thereduced valence state is particularly critical when the hydrogenationcomponent is a platinum group metal, particularly platinum. Platinum canbe found in various oxidation states in which the platinum occurs invarious positive valances. Apparently, platinum in any positive valencestate is readily stripped from a composite with alumina by the passageof aluminum chloride thereover. Therefore, it is necessary whenutilizing a platinum group metal, particularly platinum, as thehydrogenation component in combination with a refrac tory oxide, such asalumina, as the starting material in this process, to reduce theplatinum so that the platinum is in a metallic state characterized by areduced valence. Therefore, in accordance with the teaching set forthhereinabove, the hydrogenation component associated with the refractoryoxide must be in a reduced valence state, before the composite ofrefractory oxide containing a hydrogenation component can besatisfactorily utilized as the starting material in the process of thisinvention.

Following the reduction of the hydrogenation component in the catalystto a reduced valence state the catalyst composite is contacted with agaseous hydrogen halide and preferably gaseous hydrogen chloride orhydrogen bromide. The composite is contacted with the hydrogen halide ata temperature approximately the same as that. used in the other steps ofthe process and preferably in a range of from about 500 to about 650 0,although higher or lower temperatures may also be used. The amount ofhydrogen halide which is used in the treatment of the composite isdependent upon the surface area of the particular refractory oxide whichis used, an excess of hydrogen halide over the surface area of thecomposite being preferred. In addition, if so desired, the hydrogenhalide addition is also accompanied by the presence of hydrogen or aninert gas such as nitrogen. The pretreatment of the composite withhydrogen halide will split out any water which may still be present onthe composite and thus will prevent the contamination of the finishedcatalyst by the Water. The presence of water on the finished catalystwill tend to hydrolyze the Friedel- Crafts metal halide such as aluminumchloride Which is added in a subsequent step, first forming aluminumoxychloride and ultimately aluminum hydroxide, thus rendering the metalhalide inactive.

Following the pretreatment of the refractory oxidehydrogenationcomponent composite with the hydrogen halide and hydrogen, aFriedel-Crafts metal halide is added to the composite. The amount ofFriedel-Crafts metal halide utilized will range from about to about 50%based on the weight of the refractory oxide contain ing a hydrogenationcomponent, this amount depending upon the exact method of preparation.For example, if a batch type of vaporization method is utilized, abouttwo times as much Friedel-Crafts metal halide per amount of refractoryoxide containing a reduced hydrogenaiton component is used as is desiredas weight increase in the final composite. In a continuous vaporizationprocedure, this amount can be lowered to one which is just slightlygreater than the desired net weight increase of the final composite. Itis obvious that this amount, in any case, is not critical and may bevaried to arrive at the active catalyst resulting therefrom dependingupon the method of preparation and the temperature at which thecomposite is heated. Various Friedel-Crafits metal halides may beutilized but not necessarily with equivalent results. Examples of suchFriedel-Crafts metal halides include aluminum bromide, aluminumchloride, antimony pentachloride, beryllium bromide, beryllium chloride,ferric bromide, ferric chloride, gallium trichloride, stannic bromide,stannic chloride, titanium tetrabromide, titanium tetrachloride, zincbromide, zinc chloride, and zirconium chloride. Of these Friedel-Craftsmetal halides, the Friedel-Crafts aluminum halides are preferred, andaluminum chloride is particularly preferred. This is so, not onlybecause of the ease in operation in preparing the highly activecatalysts in accordance with the process of this invention, but alsobecause the thus prepared catalysts have unexpectedly high activity.

In accordance with the present process, one or more of theseFriedel-Crafts metal halides are vaporized onto a refractory oxidecontaining a reduced hydrogenation component. Suitable refractory oxidesinclude such substances as silica (a non-metallic refractory oxide), andvarious refractory metal oxides such as alumina, titanium dioxide,zirconium dioxide, chromia, zinc oxide, silica alumina, silica magnesia,silica alumina magnesia, chromia alumina, alumina boria, silicazirconia, and various naturally occurring refractory oxides of variousstates of purity such as bauxite, kaolin or bentonite clay (which may ormay not be acid treated), diatomaceous earth such as kieselguhr,montmorillonite, spinels such as magnesium oxide-alumina spinels or zincoxide-spinels, etc. Of the above mentioned refractory oxides, alumnia ispreferred and synthetically prepared gamma-alumina of a high degree ofpurity is particularly preferred.

The above mentioned refractory oxides have deposited therewith ahydrogenation component prior to pretreatment with a hydrogen halide andthe vaporization thereon of the Friedel-Crafts metal halide. Methods forsuch compositing of the hydrogenation component With the refractoryoxide are well known to those skilled in the art and includeimpregnation by means of aqueous or non-aqueous solutions of salts ofthe hydrogenation component, coprecipitation, etc., followed by dryingand calcination. Suitable hydrogenation components include the metals ofgroup VI-B and group VIII of the periodic table including chromium,molybdenum, tungsten, iron, cobalt, nickel, ruthenium, rhodium,palladium, osmium, iridium, and platinum. Of these hydrogenationcomponents, the platinum group metals are preferred, and of theseplatinum group metals, platinum and palladium are particularlypreferred. These metals are not necessarily equivalent in the resultingcatalysts and of all hydrogenation components, platinum is particularlypreferred. As set forth hereinabove, in combination with the refractoryoxide, the hydrogenation component must be in a reduced state. Suchreduced states in the case of the platinum group metals, particularlyplatinum, can be characterized by the hydrogenation component being inthe valence state of zero, that is, metallic form.

In carrying out the present process following the pretreatment of thecomposite with a hydrogen halide and, if so desired, hydrogen, thetemperature at which the Friedel-Crafts metal halide is vaporized ontothe refractory oxide containing a hydrogenation component will vary inaccordance with the particular Friedel-Crafts metal halide utilized. Insome cases, since the Friedel- Crafts metal halide decomposes on heatingto elevated temperatures, it may be necessary to carry out suchvaporization at reduced pressure to preclude such decomposition.However, in most instances, the vaporization is carried out either atthe boiling point or sublimation point of the particular Friedel-Craftsmetal halide or at temperatures not greatly exceeding these points, forexample, not greater than C. higher than the boiling point orsublimation point of the Friedel-Crafts metal halide utilized. However,in some instances it may be desirable to carry out the vaporization andsubsequent heating step at the same temperature and thus, suchtemperatures are also within the generally broad scope of the presentinvention.

This process can perhaps be best understood by a description of aspecific embodiment thereof. As set forth hereinabove, a particularlypreferred refractory oxide for use in preparing the desired catalysts isalumina. Furthermore, the alumina is preferably prepared syntheticallyand is of a high degree of purity. The methods of preparation of suchsynthetic aluminas are well known. For example, they may be prepared bythe caloination of alumina gels which commonly are formed by adding asuitable reagent such as ammonium hydroxide, ammonium carbonate, etc.,to a salt of aluminum such as aluminum chloride, aluminum nitrate,aluminum sulfate, in an amount to form aluminum hydroxide which isconverted to alumina upon drying. It has been found that aluminumchloride generally is preferred as the aluminum salt, not only forconvenience in subsequent washing and filtering procedures but alsobecause it appears to give the best results. Alumina gels are alsoprepared by the reaction of sodium aluminate with a suitable acidicreagent to cause precipitation thereof with the resultant formation ofan aluminum hydroxide gel. Synthetic aluminas may also be prepared bythe formation of alumina sols, for example, by the reaction of metallicaluminum with hydrochloric acid, which sols can be gelled by suitableprecipitation agents such as ammonium hydroxide, followed by drying andcalcination. In another embodiment, these synthetically preparedaluminas may contain from about 0.01% to about 8% combined halogen,pneferably fluorine. These halogenated aluminas may be prepared invarious manners, for example, by the addition of a suitable quantity ofhydrofluoric acid to an alumina gel prior to drying and calcinationthereof. In another manner, aluminum fluoride can be added to aluminagels thus yielding alumina having the desire-d quantity of halogencombined therewith. When the synthetically prepared alumina is preparedfrom aluminum chloride, it is sometimes advantageous and/ or desirableto minimize the washings thereof to control the desired amount ofchlorine composited with the alumina. In any of the above instanceswherein the alumina is prepared from an alumina sol or an alumina gel,the resultant product is calcined to a sufficient temperature to convertthe product into gamma-alumina. While the resultant aluminas may containrelatively small amounts of water of hydration, gamma-alumina with orwithout combined halogen is the 4 preferred synthetically preparedalumina for use as the refractory oxide in the present process.

As hereinabove set forth, the above synthetically prepared alumina willhave a hydrogenation component combined therewith, preferably a platinumgroup metal, and particularly platinum. This platinum group metal,particularly platinum, may be composited with the alumina in any of manyWell known manners. For example, an ammoniacal solution ofchloroplatinic acid may be admixed with the alumina followed by drying.In another method, chloroplatinic acid in the desired quantity can :beadded to an alumina gel slurry followed by precipitation of platinumtherefrom on the alumina by means of hydrogen sulfide or other sulfidingor precipitation agents. While the quantity of platinum combined withthe alumina is not critical, for economic reasons, the amount ofplatinum is usually kept at a minimum. Thus, large amounts of platinumdo not cause detrimental effects. Generally, however, it is preferred toutilize from about 0.01% to about 2% by weight of platinum based on thedry alumina. In another embodiment, the alumina and platinum can becomposited by coprecipitation techniques. In such a case, an aqueoussolution of the desired amount of platinum salt is admixed with asolution of an aluminum salt followed by the addition thereto of aprecipitating agent which will cause coprecipitation. The resultant gelcan be dried and calcined to form a gamma-alumina platinum compositewhich can be formed into the desired size particles.

While the physical form of the refractory oxide containing a reducedhydrogenation component is not critical, generally it is preferred toutilize macro particles so that the final composite may be used as afixed bed in a reaction zone. Thus, it is desirable to form thesynthetically prepared alumina, with or without the platinum group metalin the valence state of zero composited therewith, into pellets, forexample, of x 1 or Vs" x As", etc. This can be accomplished readily bygrinding the dried alumina gel to a powder followed by gelling thereofby known methods. Alternatively, the particles may be in the form ofspheres ,or irregularly shaped particles such as result from extrusion.While it is not intended to limit the invention to particles of anyparticular size, the above mentioned aluminaplatinum group metalcomposites are definitely preferred.

In carrying out one embodiment of the present process, the abovedescribed alumina-platinum composites in which the platinum is in areduced valence state is pretreated before the addition of aluminum chloride by passing anhydrous hydrogen chloride and hydrogen over saidcomposites at a temperature of about 600 C. whereby any water stillpresent on the composite is swept off and out of the composite.Following this the composites have vaporized thereon aluminum chloride.This can be accomplished readily by sublimation of the aluminum chlorideonto the surface of the particles. Aluminum chloride sublimes at 178 C.and thus a suitable vaporization temperature will range from about 180to about 275 C. The sublimation may be carried out under pressure ifdesired and also in the presence of diluents such as inert gasesincluding parafiin hydrocarbons, hydrogen, and nitrogen, but excludingair and other oxidizing gases. The amount of aluminum chloride whichsublimes onto the above described particles reaches a maximum at anyparticular vaporization temperature selected. In addition to vaporizingonto the aluminaplatinum composite, the aluminum chloride also reactstherewith evolving hydrogen chloride. However, it is ditficult tocontrol the exact amount of aluminum chloride which reacts. Therefore,to insure freedom of the resulant composite from free aluminum chlorideand to insure the development of maximum catalytic activity, thecomposite is heated at a temperature above about 400 C. for a sufiicienttime to remove therefrom any unreacted aluminum chloride. Since aluminumchloride sublimes at 178 C., this heating treatment in the absence offurther added aluminum chloride results in freeing the composite fromfree aluminum chloride. However, since aluminum chloride itself istenaciously held onto an aluminum surface, temperatures at least as highas 300 C. are required. When the composite is further heated at atemperature above 400 C., maximum catalytic activity is developed aswill be set forth further hereinafter. This high temperature (above 400C.) heating treatment may accomplish further reaction of the unreactedaluminum chloride with the alumina-platinum composite thereby insuringfreedom of the resultant composite from unreacted aluminum chloride. Insome cases, if the aforementioned pretreatment is omitted the hydrogenchloride evolution is preceded by evolution of water. The hydrogenchloride evolution is thought to be due to the reaction of aluminumchloride with hydroxyl groups on the alumina surface. A portion of thishydrogen chloride can react with hydroxyl groups, thus freeing water. Ashereinbefore set forth the presence of water can contaminate thecomposite, thus lowering the activity of the finished catalyst andshortening the life thereof. However, the final catalyst composite isfree from free aluminum chloride and it is the process which results inthe unusual catalytic properties of the resultant composite. One unusualfeature of catalysts which are prepared in the above described manner isthat these catalysts may be utilized for reactions for which it hasheretofore been considered necessary to use large amounts of hydrogenhalide promoters along 'with free FriedelCrafts metal halides such asaluminum chloride. While the use of hydrogen halide promoters with thecatalyst compositions of the present invention is not meant to beexcluded, it has been found unnecessary to utilize them in such largequantities and in some cases in any quantity to obtain satisfactoryresults from these compositions.

As set forth hereinabove, the composite of refractory oxide containing areduced hydrogenation component and Friedel-Crafts metal halide isheated at a temperature above about 400 C. for a time sufiicient toremove therefrom. any unreacted Friedel-Crafts metal halide. The exacttemperature to be utilized will depend upon the boiling point orsublimation temperature of the particular Friedel-Crafts metal halideutilized. In general, particularly with aluminum chloride, temperaturesof about 400 to about 700 C. in times of from about 1 to about 48 hoursare satisfactory. Furthermore, the refractory oxides containinghydrogenation components in a reduced valence state as set forthhereinabove are selected as substances suitable as catalyst supports forvarious reasons. One reason is that these substances, such as analumina-platinum composite in which the the platinum is in a reducedvalence state, have high surface areas which appear to have a beneficialeffect upon catalyst activity. In many cases, these high surface areasare developed in the preparation of such supports under carefullycontrolled conditions of heating at specific temperatures for specificperiods of time. Therefore, in the heating process step of the presentinvention, whether carried out simultaneously or subsequently to thevaporization of the Friedel-Crafts metal halide, care must be taken sothat these high surface areas are not destroyed by the aforementionedheat treatment. Therefore, it is definitely disadvantageous to carry outsuch heat treatments at temeratures above about 700 C. Of course, it isobvious that such temperatures are inter-related with the time at whichsuch refractory oxides containing reduced hydrogenation components arekept at these temperatures. Therefore, care is asserted in all instancesto maintain maximum surface area during the subsequent heating of thecatalyst composites in the process of this invention.

As set forth hereinbefore with reference to the vaporization of theFriedel-Crafts metal halide onto the composite of a refractory metaloxide containing a reduced hydrogenation component, the heating step canbe carried out in the presence of various inert diluent gases. Suchgases include methane, hydrogen, and parafiinic hydrocarbons includingmethane, ethane, etc. These gases do not have an adverse effect on theresultant catalyst activity. Furthermore, they do not allow oxidation ofthe hydrogenation component so that stripping thereof as set forthhereinabove from the composite can be accomplished by the passage of theFriedel-Crafts metal halide thereover. When the vaporization step andtie heating step are combined, one or more of the above gases may beutilized as the carrier gas for the Friedel-Crafts metal halide as Wellas providing a. proper atmosphere for the heating step. The use of thissimultaneous vaporization and heating technique as well as the two stepvaporization and subsequent heating technique method of preparation willbe illustrated fully in the examples.

Furthermore, as will be demonstrated in the examples, this simultaneousor subsequent heating step results in catalyst composites ofunexpectedly high activity for certain hydrocarbon conversion reactions.Thus, the catalysts formed in accordance with the process of the presentinvention are superior to composites comprising refractory oxides andfree Friedel-Craf-ts metal halide-s. Furthermore, as set forthhereinabove, the vaporization and heating steps can be carried outsimultaneously in a one-step process if so desired. For example, asuitable gamma-alumina platinum composite may be placed in a glass orsteel tube in a furnace, the composite may then be pretreated withhydrogen chloride and hydrogen, following which the furnace is broughtto the desired heating temperature and vapors of the Friedel-Craftsmetal halide such as aluminum chloride passed there over. Thepreparation of such a composite will be set forth in further detail inthe examples.

The processes of the present invention and particularly theisomerization of normal paraffins to branched chain parafiins may beeffected in any suitable manner and may comprise either a batch or acontinuous type operation. For example, when a batch type operation isused a quantity of the normal paraffin to be isomerized is placed in anappropriate apparatus along with the particular catalytic composition ofmatter. The apparatus is then heated to the desired temperature andmaintained thereat for a predetermined period of time at the end ofwhich time the apparatus and contents thereof are cooled to roomtemperature. The reaction mixture is recovered, separated from thecatalyst, and subjected to fractional distillation whereby the desiredisomerized products are separated from any unreacted starting materials.

In addition the processes of this invention may be effected in acontinuous manner of operation, the particular type of operationdepending upon the form in which the catalyst is used.

The process may be eii'ected in any suitable manner, which will not onlydepend upon the particular reaction but also upon the form in which thecatalyst is used, When the catalyst is utilized as a solid mass, it maybe disposed as a fixed bed in a reaction zone, and the reactants aresupplied thereto in any suitable manner. Reactants may be passed inupward flow or downfiow through the catalyst bed. In another manner, thecatalyst may be utilized in a so-called fluidized fixed bed type ofoperation in which the catalyst is maintained in a turbulent state bypassage of the reactants therethrough. In another method of operation,the catalyst may be utilized as particles of suitable size so that theywill be fluidized along with the reactants and passed to a reaction zonefrom which the catalyst is continuously separated from the reactionproducts. In any case, as hereinbefore set forth, the catalyst may befurther activated, if desired, by the utilization therewith of ahydrogen halide such as hydrogen chloride or hydrogen bromide. Inanother embodiment, the hydrogen halide may be introduced in the form ofa suitable organic compound such as an alkyl halide from which thehydrogen halide -is formed under the reaction conditions. Examples ofeach allryl halides including propyl chloride, butyl chloride, amylchloride, propyl bromide, butyl bromide, amyl bromide, etc. Also, it iswithin the scope of the present invention to utilize the hydrogen halidepromoter continuously or intermittently as may be desired in anyparticular case. Regardless of the particular operation employed, theproducts are fractionated or otherwise separated to recover the desiredproducts and to separate unconverted material for recycling. Hydrogenhalide in the eflluent product likewise is separated and may be recycledif desired.

The following examples, which are given to illustrate further thenovelty and utility of the present invention are not, however, intendedto limit the generally broad scope of the present invention in strictaccordance therewith.

Example I Gamma-alumina was prepared by the general method of dissolvingaluminum pellets in hydrochloric acid to form a sol containing 15%alumina. Hydrofiuoric acid was added to the sol so that the finalcomposite contained 0.375% fluorine by weight based on dry alumina. Theresulting solution was mixed with hexamethylene tetramine in acontinuous mixer and dropped into an oil bath at about C. to formspheres. The spheres were aged in the oil, and then in an aqueoussolution of ammonia for about one to two hours. The washed spheres werethen transferred to a drier, dried at about 250 C., and calcined atabout 600 C.

A sufiicient quantity of the synthetically prepared gamma-aluminaspheres, as described above, was impregnated with a dilute ammoniacalsolution of chloroplatinic acid. The amount of platinum in this solutionwas adjusted so that the final composite contained 0.375% platinum byweight based on the dry alumina. A suflicient quantity of thisplatinum-alumina composite was prepared so that it could be used in thepreparation of various further composites.

A 50 cc. quantity of the above prepared composite was placed as a fixedbed in a reaction tube and tested for activity for the isomerization ofnormal butane to isobutane. Conditions utilized included a pressure of300 p.s.i.g., a hydrogen to hydrocarbon mol ratio of 0.5, 1.0 liquidhourly space velocity, and various temperatures. This composite isvirtually inactive for the isomerization of normal butane to isobutaneduring two hour test periods at temperatures of C., 200 C., 250 C., 300C., and 350 C. At about 400 C., about 1.5% isobutane appears in theproduct.

Example II A platinum-alumina composite (107.1 g.) prepared as describedin Example I above was reduced in hydrogen for two hours at 600 C. andthen placed as a fixed bed in a glass tube surrounded by a verticalfurnace. Following this a mixture of anhydrous hydrogen chloride andhydrogen was passed through the composite at a temperature of about 600C. for a period of about 3 hours. Following this the bottom end of theglass tube was connected to a glass flask containing 43 g. of anhydrousaluminum chloride. The temperature of the platinum-alumina composite inthe tube was adjusted to 200 C. and heat applied to the glass flaskcontaining the aluminum chloride until it began to sublime. A stream ofnitrogen gas was then passed through a glass inlet tube into the glassflask to carry the aluminum chloride vapors up through theplatinum-alumina composite being maintained at 200 C. This was continuedfor three hours after which time the aluminum chloride vapors wereobserved at the ascendant or top of the glass tube containing theplatinum-alumina composite.

Fifteen cc. of the thus prepared composite was tested for isomerizationof normal butane at the conditions hereinafter set forth, namely, 500p.s.i.g., 1:1 hydrogen to hydrocarbon mole ratio, 4.0 liquid hourlyspace velocity,

l 1 hours total on stream time and at various temperatures. At 160 C.,there was a 32 weight percent isobutane conversion; at 180 C., 48 weightpercent isobutane conversion and at 200 C., 55 weight percent isobutaneconversion was observed.

Example III A platinum-alumina composite was prepared in a mannersimilar to that set forth in Example I above and was reduced in hydrogenfor 2 hours at 600 C., the final composite containing 0.2% platinum.Following this the composite was placed in a glass tube and anhydroushydrogen chloride and hydrogen were passed through said composite alsoat a temperature of 600 C. Following this the catalyst as a fixed bed ina glass tube was connected to a glass flask containing anhydrousaluminum chloride. The temperature was adjusted to 200 C. the sublimedaluminum chloride passed through the catalyst composite. Following theimpregnation of the composite with the sublimed aluminum chloride, saidimpregnation being effected by the addition of a stream of nitrogenwhich carried the sublimed aluminum chloride up through the composite,the composite was allowed to cool.

Fifteen cc. of the thus prepared composite was tested for isomerizationof normal butane at conditions similar to that set forth in Example IIabove, namely, 500 p.s.ig. 1:1 hydrogen to hydrocarbon mole ratio, 4.0liquid hourly space velocity and at various temperatures. At 160 C., 36weight percent isobutane conversion was noted; at 180 C., 50 weightpercent isobutane conversion was observed and at 200 C., weight percentisobutane conversion was observed in the product.

Example IV The composite which was utilized in this example was preparedin substantially the same manner as hereinbefore described in the aboveexamples, the only change being that palladium was used in place ofplatinum. The palladium-alumina composite was reduced with hydrogen at atemperature of 600 C., the composite containing 0.2% palladium.Following this the catalyst was pretreated with anhydrous hydrogenchloride and hydrogen to split out any water which was still present onthe catalyst. The thus pretreated composite was then treated withaluminum chloride in a manner similar to that hereinbefore set forth and15 cc. of catalyst was tested for activity in a manner similar to thatset forth in the above examples. The conditions were identical, that is,500 p.s.i.g., 1:1 hydrogen to hydrocarbon mole ratio, 4.0 liquid hourlyspace velocity and various temperatures. At C., a 37 weight percentisobutane conversion was noted; at C., a 52 weight percent isobutaneconversion was observed and at 200 C., a 56 weight percent isobutaneconversion was observed.

Example V A platinum-alumina composite is prepared in a manner similarto that set forth in Example I above. Following this theplatinum-alumina composite is reduced with hydrogen at a temperature ofabout 600 C. for a period of about 3 hours. Following this the catalystas a fixed bed in a glass tube is connected to a glass fiaslr containinganhydrous aluminum chloride. The temperature is adjusted to 200 C. andthe sublimed aluminum chloride is passed through the catalyst composite.Following the impregnation of the composite with the sublimed aluminumchloride, said impregnating being effected by the addition of a streamof nitrogen which carries the sublimed aluminum chloride up through thecomposite, the composite is allowed to cool.

Fifteen cc. of this composite is placed as a fixed bed in a reactiontube and is tested for activity for the isomerization of normal pentaneto isopentane. Conditions utilized for the isomerization process includea pressure of about 500 p.s.i., a hydrogen to hydrocarbon mole ratio 1.2of 121, a liquid hourly space velocity of about 4.0 and at temperaturesranging from about 160 to about 200 C. There will be observed anapproximate 50% conversion of n-pentane to isopentane.

I claim as my invention:

1. A process for producing branched chain hydrocarbons which comprisesisomerizing normal hydrocarbons in the presence of a catalyst preparedby treating a composite of a refractory inorganic oxide supportcontaining a platinum group metal, the platinum group metal beingcharacterized by being in a reduced valence state, with a hydrohalide ata temperature in the range of from about 500 to about 650 C., thereaftervaporizing a Fricdel- Crafts metal halide onto said composite, andheating the thus formed composite at a temperature above 400 C. for atime sufficient to remove therefrom any unreacted Friedel-Crafts metalhalide.

2. A process for producing branched chain hydrocarbons which comprisesisomerizing normal hydrocarbons at a temperature in the range of fromabout 0 to about 300 C. and at a pressure in the range of from aboutatmospheric to about 5000 p.s.i. in the presence of a catalyst preparedby treating a composite of a refractory inorganic oxide supportcontaining a platinum group metal, the platinum group metal beingcharacterized by being in a reduced valence state, with a hydrohalide ata temperature in the range of from about 500 to about 650 C., thereaftervaporizing a Friedel-Crafts metal halide onto said composite, andheating the thus formed composite at a temperature above 400 C. for atime sufficient to remove therefrom any unreacted Friedel- Crafts metalhalide.

3. A process for producing branched chain hydrocarbons which comprisesisomerizing normal hydrocarbons at a temperature in the range of fromabout 0 to about 300 C. and at a pressure in the range of from aboutatmospheric to about 5000 p.s.i. in the presence of a catalyst preparedby treating a composite of alumina containing a platinum group metal,the platinum group metal being characterized by being in a reducedvalence state, with a hydrohalide at a temperature in the range of fromabout 500 to about 650 C., thereafter vaporizing a Friedel-Crafts metalhalide onto said composite, and heating the thus formed composite at atemperature above 400 C. for a time sufficient to remove therefrom anyunreacted Friedel-Crafts metal halide.

4. A process for producing branched chain hydrocarbons which comprisesisomerizing normal hydrocarbons at a temperature in the range of fromabout 0 to about 300 C. and at a pressure in the range of from aboutatmospheric to about 5000 p.s.i. in the presence of a catalyst preparedby treating a composite of alumina containing platinum, the platinumbeing characterized by being in a reduced valence state, with ahydrohalide at a temperature in the range of from about 500 to about 650C., thereafter vaporizing a Friedel-Crafts metal halide onto saidcomposite, and heating the thus formed composite at a temperature above400 C. for a time suflicient to remove therefrom any unreacted Friedel-Crafts metal halide.

5. A process for producing branched chain hydrocarbons which comprisesisomerizing normal hydrocarbons at a temperature in the range of fromabout 0 to about 300 C. and at a pressure in the range of from aboutatmospheric to about 5000 p.s.i. in the presence of a catalyst preparedby treating a composite of alumina containing platinum, the platinumbeing characterized by being in a reduced valence state, with hydrogenchloride at a temperature in the range of from about 500 to about 650C., thereafter vaporizing aluminum chloride onto said composite, andheating the thus formed composite at a temperature in the range of fromabout 400 to about 700 C. for a time sufficient to remove therefrom anyunreacted aluminum chloride.

6. A process for producing branched chain hydrocarbons which comprisesisomerizing normal hydrocarbons at a temperature in the range of fromabout to about 300 C. and at a pressure in the range of from aboutatmospheric to about 5000 p.s.i. in the presence of a catalyst preparedby treating a composite of alumina containing palladium, the palladiumbeing characterized by being in a reduced valence state, with hydrogenchloride at a temperature in the range of from about 00 to about 650 C.,thereafter vaporizing aluminum chloride onto said composite, and heatingthe thus formed composite at a temperature in the range of from about400 to about 700 C. for a time sufiicient to remove therefrom anyunreacted aluminum chloride.

7. A process for producing branched chain hydrocarbons which comprisesisomerizing normal hydrocarbons at a temperature in the range of fromabout 0 to about 300 C. and at a pressure in the range of from aboutatmospheric to about 5000 p.s.i. in the presence of a catalyst preparedby treating a composite of alumina containing platinum metal, theplatinum metal being characterized by being in a reduced valence state,with hydrogen chloride and hydrogen at a temperature in the range offrom about 500 to about 650 C., thereafter vaporizing aluminum chlorideonto said composite, and heating the thus formed composite at atemperature in the range of from about 400 to about 700 C. for a time offrom about 1 to about 48 hours to remove therefrom any unreactedaluminum chloride.

8. A process for producing branched chain hydrocarbons which comprisesisomerizing normal hydrocarbons at a temperature in the range of fromabout 0 to about 300 C. and at a pressure in the range of from aboutatmospheric to about 5000 p.s.i. in the presence of a catalyst preparedby treating a composite of alumina containing platinum metal, theplatinum metal being characterized by being in a reduced valence state,with hydrogen bromide and hydrogen at a temperature in the range of fromabout 500 to about 650 C., thereafter vaporizing aluminum chloride ontosaid composite, and heating the thus formed composite at a temperaturein the range of from about 400 to about 700 C. for a time of from about1 to about 48 hours to remove therefrom any unreacted aluminum chloride.

9. A process for producing an isoparaflin which comprises isomerizing anormal paraffin at a temperature in the range of from about 0 to about300 C. and at a pressure in the range of from about atmospheric to about5000 p.s.i. in the presence of a catalyst prepared by treating acomposite of a refractory inorganic oxide containing a platinum groupmetal, the platinum group metal being characterized by being in areduced valence state, with a hydrohalide at a temperature of from about500 to about 650 C., thereafter vaporizing a *Friedel-Crafts metalhalide onto said composite and heating the thus formed composite at atemperature above 400 C. for a time suflicient to remove therefrom anyunreacted Friedel-Crafts metal halide.

10. A process for producing isobutane which comprises isomerizing normalbutane at a temperature in the range of from about 0 to about 300 C. andat a pressure in the range of from about atmospheric to about 5000p.s.i. in the presence of a catalyst prepared by treating a composite ofa refractory inorganic oxide containing a platinum group metal, theplatinum group metal being characterized by being in a reduced valencestate, with a hydrohalide at a temperature of from about 500 to about650 C., thereafter vaporizing a Friedel-Crafts metal halide onto saidcomposite and heating the thus formed composite at a temperature above400 C. for a time sufficient to remove therefrom any unreacted Friedel-Crafts metal halide.

11. A process for producing isopentane which comprises isornerizingnormal pentane at a temperature in the range of from about 0 to about300 C. and at a pressure in the range of from about atmospheric to about5000 p.s.i. in the presence of a catalyst prepared by treating acomposite of a refractory inorganic oxide containing a platinum groupmetal, the platinum group metal being characterized by being in areduced valence state, with a hydrohalide at a temperature of from about500 to about 650 C., thereafter vaporizing a Friedel-Crafts metal halideonto said composite and heating the thus formed composite at atemperature above 400 C. for a time sufficient to remove therefrom anyunreacted Friedel- Crafts metal halide.

12. A process for producing isobutane which comprises isomerizing normalbutane at a temperature in the range of from about 0 to about 300 C. andat a pressure in the range of from about atmospheric to about 5000p.s.i. in the presence of a catalyst prepared by treating a composite ofalumina containing platinum metal, the platinum metal beingcharacterized by being in a reduced valence state, with hydrogenchloride and hydrogen at a temperature in the range of from about 500 toabout 650 C., thereafter contacting said composite with vapors ofanhydrous aluminum chloride at a temperature in the range of from about400 to about 700 C. for a time of from about 1 to about 48 hours,whereby simultaneous reaction of the aluminum chloride with saidcomposite and heating of the resultant composite to remove unreactedaluminum chloride is accomplished as a single step.

13. A process for producing isopentane which comprises isomerizingnormal pentane at a temperature in the range of from about 0 to about300 C. and at a pressure in the range of from about atmospheric to about5000 p.s.i. in the presence of a catalyst prepared by treating acomposite of alumina containing platinum metal, the platinum metal beingcharacterized by being in a reduced valence state, with hydrogenchloride and hydrogen at a temperature in the range of from about 500 toabout 650 C., thereafter contacting said composite with vapors ofanhydrous aluminum chloride at a temperature in the range of from about400 to about 700 C. for a time of from about 1 to about 48 hours,whereby simultaneous reaction of the aluminum chloride with saidcomposite and heating of the resultant composite to remove unreactedaluminum chloride is accomplished as a single step.

References Cited in the file of this patent UNITED STATES PATENTS2,924,629 Donaldson Feb. 9, 1960

1. A PROCESS FOR PRODUCING BRANCHED CHAIN HYDROCARBONS WHICH COMPRISESISOMERIZING NORMAL HYDROCARBONS IN THE PRESENCE OF A CATALYST PREPAREDBY TREATING A COMPOSITE OF A REFRACTORY INORGANIC OXIDE SUPPORTCONTAINING A PLATINUM GROUP METAL, THE PLATINUM GROUP METAL BEINGCHARACTERIZED BY BEING IN A REDUCED VALENCE STATE, WITH A HYDROHALIDE ATA TEMPERATURE IN THE RANGE OF FROM ABOUT 500* TO ABOUT 650* C.,THEREAFTER VAPORIZING A FRIEDELCRAFTS METAL HALIDE ONTO SAID COMPOSITE,AND HEATING THE THUS FORMED COMPOSITE AT A TEMPERATURE ABOVE 400* C. FORA TIME SUFFICIENT TO REMOVE THEREFROM ANY UNREACTED FRIEDEL-CRAFTS METALHALIDE.